Merge #19219: Replace automatic bans with discouragement filter

2ad58381fffb33d611abf900b73d9e6b5a4e35f8 Clean up separated ban/discourage interface (Pieter Wuille)
b691f2df5f7d443c0c9ee056ab94aa0fc19566d5 Replace automatic bans with discouragement filter (Pieter Wuille)

Pull request description:

  This patch improves performance and resource usage around IP addresses that are banned for misbehavior. They're already not actually banned since #14929, as connections from them are still allowed, but they are preferred for eviction if the inbound connection slots are full.

  Stop treating these like manually banned IP ranges, and instead just keep them in a rolling Bloom filter of misbehaving nodes, which isn't persisted to disk or exposed through the ban framework. The effect remains the same: preferred for eviction, avoided for outgoing connections, and not relayed to other peers.

  Also change the name of this mechanism to "discouraged" to better reflect reality.

ACKs for top commit:
  naumenkogs:
    utACK 2ad58381fffb33d611abf900b73d9e6b5a4e35f8
  amitiuttarwar:
    code review ACK 2ad58381ff
  jonatack:
    ACK 2ad5838 per changes since last review `git range-diff 3276c14 1f7e0ca 2ad5838`
  jnewbery:
    Code review ACK 2ad58381fffb33d611abf900b73d9e6b5a4e35f8

Tree-SHA512: 5dedef401d9cbfa026812651303e6286223563dbeed7a10766ed536ac9e3f29ed4bd0df29cc6deadceeb35cbe9f066346add14ef0833958ca9f93d123fe7aab5

1 files changed, 3 insertions, 25 deletions

diff --git a/src/addrdb.h b/src/addrdb.h
index c6d4307d69..8410c3776c 100644
--- a/src/addrdb.h
+++ b/src/addrdb.h
@@ -17,13 +17,6 @@ class CSubNet;
 class CAddrMan;
 class CDataStream;
 
-typedef enum BanReason
-{
-    BanReasonUnknown          = 0,
-    BanReasonNodeMisbehaving  = 1,
-    BanReasonManuallyAdded    = 2
-} BanReason;
-
 class CBanEntry
 {
 public:
@@ -31,7 +24,6 @@ public:
     int nVersion;
     int64_t nCreateTime;
     int64_t nBanUntil;
-    uint8_t banReason;
 
     CBanEntry()
     {
@@ -44,31 +36,17 @@ public:
         nCreateTime = nCreateTimeIn;
     }
 
-    explicit CBanEntry(int64_t n_create_time_in, BanReason ban_reason_in) : CBanEntry(n_create_time_in)
+    SERIALIZE_METHODS(CBanEntry, obj)
     {
-        banReason = ban_reason_in;
+        uint8_t ban_reason = 2; //! For backward compatibility
+        READWRITE(obj.nVersion, obj.nCreateTime, obj.nBanUntil, ban_reason);
     }
 
-    SERIALIZE_METHODS(CBanEntry, obj) { READWRITE(obj.nVersion, obj.nCreateTime, obj.nBanUntil, obj.banReason); }
-
     void SetNull()
     {
         nVersion = CBanEntry::CURRENT_VERSION;
         nCreateTime = 0;
         nBanUntil = 0;
-        banReason = BanReasonUnknown;
-    }
-
-    std::string banReasonToString() const
-    {
-        switch (banReason) {
-        case BanReasonNodeMisbehaving:
-            return "node misbehaving";
-        case BanReasonManuallyAdded:
-            return "manually added";
-        default:
-            return "unknown";
-        }
     }
 };